1. Field of the Invention
The field of the invention as established in and by the United States Patent Office is believed to be found in gear reducers and in particular those using cycloid gearing and operation. This gear reducer of this invention pertains to reductions as low as 3.4 to as high as 7569 to one with compactness, lightness, high efficiency and low heat. A special nutating internal member and a special tooth form are used to provide the efficiency of operation.
2. Description of the Prior Art
Gear reducers are well known and are provided with drive means to change speeds of the input device to a desired output speed. There are many types of reducers, including parallel shaft gearing, bevel gearing, compound gearing, worm gearing and planetary gearing. In ordinary parallel shaft gear practice, it is reasonable to handle ratios from 1:1 to about 8:1 in a single reduction. A ratio of 120:1 requires a triple reduction unit which has three sets of pinions and gears or a total of six toothed parts. With a worm set (non-intersecting and angled) it is possible to handle 100:1 or more in a single reduction with only two toothed parts, but efficiency is low and the heat generation is high. Planetary concentric shaft drives range from 1.2:1 to 25:1.
Conventional gear drives incorporate involute generated tooth forms because of their interchangeability and because they do not ordinarily require as stringent a manufacturing tolerance. Another related type of concentric shaft speed changer incorporates a special tooth form known as cycloidal. With this form of tooth generation, contact between teeth occurs over an effective arc of 90 degrees to 120 degrees rather than the 7 degrees to 20 degrees for the conventional involute gear form. Precision of cycloid gearing manufacture is more demanding, but with modern machine technologies the advantages far outweigh the cost. These advantages include much smaller, lighter, quieter and more efficient transmission units because of their longer arc of engagement.